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单选题
When disassembling or assembling an injection pump plunger and barrel you should （）
A
keep the parts immersed in diesel fuel
B
always keep the plunger and barrel together
C
work over a linoleum-type surface
D
all of the above
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考题
The plunger in a jerk pump is rotated until the release port is uncovered If the port remains uncovered all of the time, which of the listed operations will occur?A.No fuel will be deliveredB.The maximum effective stroke will be attainedC.The fuel delivered to the cylinder will be excessiveD.The injection nozzle will overheat and carbonize
考题
As the plunger moves upwards in the barrel, injection will commence once the plunger bas_______the spill ports and the pressure builds up.A.opened upB.closed offC.lined upD.taken off
考题
An increase in the fuel injection pump discharge pressure can be caused by a/an _______.A.leaking delivery valveB.excessive bearing end playC.plugged injector spray holeD.increased plunger stroke
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The amount of fuel delivered by a helical plunger fuel injection pump is controlled by ______.A.varying the pump discharge pressureB.varying the pump return pressureC.rotation of the pump plungerD.rotation of the pump barrel
考题
单选题In a jerk pump, the amount of fuel that will be forced through the spray nozzle on each upward stroke of the plunger depends on （）A
the pump supply pressureB
the slope of the fuel camC
how the plunger is rotatedD
the number of sleeve segments engaged with the rack
考题
单选题Movement of the pump control rack in a fuel injection system using individual plunger-type pumps （）A
changes the position of the fuel inlet portsB
changes the length of the pump strokeC
varies the quantity of fuel deliveredD
varies the compression of the delivery valve spring
考题
单选题The injector pump is operated by a cam which drives the plunger （）.A
top and bottomB
to and froC
up and downD
back and forth
考题
单选题The plunger in the fuel injector pump, usually operated by a （）, is driven up and down when working.A
crankshaftB
camshaftC
piston rodD
rack and pinion
考题
单选题A common trouble with the fuel pump plunger or fuel valve spindle is （）.A
water leakageB
steam leakageC
oil leakageD
air leakage
考题
单选题Diesel engine injection lag is caused by（）A
compressibility of the fuelB
high fuel oil supply flowC
scored plunger and barrel packingD
excessive air turbulence
考题
单选题The fuel injector pump is operated by （） which drives the plunger up and down.A
a separate motorB
a camC
a generatorD
a chain
考题
单选题In a unit injector the amount of fuel that will be forced through the spray nozzle on each stroke of the plunger depends on （）A
the pump supply pressureB
the slope of the fuel camC
how the plunger is rotatedD
the number of sleeve segments engaged with the rack
考题
单选题It is important to note that the injection only takes place when the plunger is moving up the cam （）.A
base circleB
slopeC
bottom pointD
top point
考题
单选题An individual injection pump is designed for variable beginning and constant ending of injectionFor diesel engines operating at constant speeds, the start of injection will（）A
advance as the load increasesB
retard as the load increaseC
remain unchanged regardlessD
always occur at top dead center
考题
单选题The major cause of fuel pump and injection system problems is （）A
improper adjustmentsB
contaminated fuelC
kinked fuel linesD
excessive engine vibration
考题
单选题The effective pump stroke of an individual port-and-helix fuel injection pump is determined by the （）A
fuel delivery pressureB
pump plunger diameterC
plunger control rack positionD
total pump stroke
考题
单选题Faulty operation of diesel engine fuel injection nozzles can be directly caused by （）.A
water in the fuel oil supplyB
excessive fuel nozzle holder coolingC
a distorted fuel spray patternD
leakage past the plunger into the oil drain
考题
单选题When disassembling or assembling an injection pump plunger and barrel you should （）A
keep the parts immersed in diesel fuelB
always keep the plunger and barrel togetherC
work over a linoleum-type surfaceD
all of the above
考题
单选题Fuel injection uses the jet pump system and a Woodward type hydraulic （） is used to control engine speed.A
controllerB
governorC
instrumentD
apparatus
考题
单选题An increase in the fuel injection pump discharge pressure can be caused by a/an （）A
leaking delivery valveB
excessive bearing end playC
plugged injector spray holeD
increased plunger stroke
考题
单选题Which of the fuel injection systems listed uses a spring loaded differential spray needle valve and individual pump for each cylinder?（）A
Common-rail injectionB
Air injectionC
Jerk pump injectionD
Distribution injection
考题
单选题In a common rail engine, the fuel is injected into cylinders（）A
by injection pumpsB
at a time decided by the injection pump timingC
by a signal opening the magnetic valvesD
at a time decided by the cam directly
考题
单选题When the follower is on the base circle of the cam, the pump plunger is at the （） of its stroke.A
topB
middleC
bottomD
any of the above
考题
单选题A centrifugal pump vibrates excessively during operationUpon disassembling the pump it is found that the impeller is out of balanceWithout an available spare, you should （）.A
drill holes through the heavy side of the impeller until it balancesB
weld counterweights to the light side of the impellerC
remove metal from the heavy side by machining in a latheD
acid wash and serape the heavy side until it balances
考题
单选题As the plunger moves upwards in the barrel, injection will commence once the plunger has （） the spill ports and the pressure builds up.A
opened upB
closed offC
lined upD
taken off
考题
单选题If the plunger or barrel of a fuel injection jerk pump becomes damaged,（）A
only the replacement of the entire pump would be acceptableB
the injection pump and injection nozzle must be replacedC
either the barrel or plunger must be replacedD
the barrel and plunger must be replaced as a unit
考题
单选题The amount of fuel delivered by a helical plunger fuel injection pump is controlled by （）A
varying the pump discharge pressureB
varying the pump return pressureC
rotation of the pump plungerD
rotation of the pump barrel
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